Abstract : A twin indicator miniature equivalent of the 6AF6G was develope d. The solder glass, poli-optic sealing, and fused glass techniques were employed in an effort to seal the tube in a vacuum after processing. It was concluded that it was impractical to seal a tube together in the bell jar under vacuum with a glass-to-glass seal. Another method was tried which consisted of sealing the bulb and stem in the usual manner and exhausting through a tubulation in the stem. To eliminate the projecting tip-off, the glass had to be mashed down while still soft. The first tubes made in this fashion developed stem cracks. Test diodes were made using Pb glass bulbs. Prior to tipping-off, the getters were flashed lightly to absorb gas liberated from the glass during the annealing period; however Pb was reduced out of the glass. Life tests indicated that tubes having soft glass (lime) envelopes can be made to operate at bulb temperatures up to 400 deg C.